I would like to set up a small care home for 3 people with learning disabilities how do I do this

Depends on what country you are in ? US, Canada, France or so on, we are a international site.

Do you wish to receive funding though Medicare and Medicaid?

In the US, some very basics, Get your care home licensed and it will have to be zoned for this type of business. Have proper insurance. Get all of the equipment and other safety requirements as required under zoning code and Medicare/Medicaid laws and rule.

Locally here, your kitchen will have to be inspected and meet heath department rules.
Inspection and approval by Fire Marshall
Inspection and certification and license with Medicare/Medicaid to allow billing.

I will assume you understand all of the paperwork requirements for resident records, billing and the such, since there are manuals full of requirements just on paper work